1. Field of the Invention
The present invention relates to a retainer adapted to be installed in a rolling bearing, in particular, a roller bearing for use in iron and steel making equipment, construction equipment, railway cars as well as general industrial machinery.
2. Description of the Related Art
A machined retainer is known as a retainer adapted to be installed in a rolling bearing for use in general industrial machinery and which is of high accuracy, and a metallic split-type machined retainer is common as a machined retainer for roller bearings.
As shown in FIG. 14, this split-type machined retainer comprises two components 52, 53 which are a pocket forming component 52 comprising in turn a plurality of pillars 50 arranged in a revolving direction of the retainer and a side plate 51, and a flange component 53 constituting the other side plate of the retainer, and in a split state, the pocket forming component 52 is machined from an axial direction X of the retainer so as to finish pockets 55 thereof such that a side 50a of the pillar 50 facing in the retainer revolving direction Y (a pocket surface of the pillar 50) is formed into any sectional configuration.
In an integral one-piece machined retainer, it is common that the sectional configuration of the pocket is straight along a radial direction Z of the retainer. For example, in an integral one-piece machined retainer for a ball bearing, as shown in a sectional view of FIG. 15, the pocket 55 is formed into a cylindrical configuration.
In addition, in a plastic retainer, since it is injection molded, even with an integral one-piece retainer, it is possible to form pockets into various sectional configurations.
In the split-type machined retainer, the pockets 55 are machined for finishing by inserting a machining part such as a milling cutter on a spindle of a tool in a prepared hole for the pocket with the spindle being oriented toward the retainer axial direction X and then translating the machining part so inserted in a direction normal to the retainer axial direction X for cutting. This inevitably generates burrs at portions where inside and outside diameter surfaces of the retainer main body and the pockets 55 intersect with each other, and therefore there needs a process posterior to the machining process for de-burring.
In addition, after the pockets 55 are machined for finishing there also needs a clamping process for fixing together the pocket forming component 52 and the flange component 53 which are separated. In this clamping process, the flange component 53 needs to be rivet joined to the pillars 50 of the pocket forming component 52, but the size allowed for a rivet 54 or a boss for use in fastening and fixing the components together is inevitably restricted by the specification of a bearing in which the retainer is to be installed. This may lead to a limitation to the strength of the pillars of the retainer.
On the other hand, when thinking of a retainer for a roller bearing, in a case where the pockets 55 are machined for finishing through milling and broaching, it is general from the fact that cutting is carried out in a state in which the spindle (the rotating shaft) of a cutting tool is oriented toward the retainer axial direction X that corner radii in the four corners of the pockets 55 are inevitably formed smaller than corner radii of end faces of rolling elements. In this conventional construction, great stress concentration is caused at the respective four corners of the pockets by the rolling elements while the bearing is in use, problems being thereby caused in relation to the accuracy and life of the retainer.
In addition, the above machining method for finishing cannot be used for the integral one-piece machined retainer.
On the other hand, in the integral one-piece machined retainer, as described above, the pockets 55 are generally formed into a straight configuration in section along the retainer radial direction, and in many cases this inevitably limits the guiding method for the retainer to a race guiding type. In order to make this integral one-piece machined retainer a rolling element guiding type, there needs a further machining process posterior to the process for machining the pocket 55 for finishing for providing in the pocket 55 a run-out preventing portion (an engagement portion) for control guiding a rolling element.
On the other hand, in the plastic retainer, in many cases the application thereof to a bearing is limited in terms of environment and specification by problems of strength and temperature caused in relation to the material (resin) of the case, and therefore an integral one-piece retainer has been demanded which can stand for a wider range of service conditions.